The invention relates to apparatus as well as to a method for exposing light-sensitive material such as photographic paper. The apparatus includes an exposure device, an exposure stage, at least one magazine for storing a roll of light-sensitive material, a transport device for transporting the light-sensitive material from the magazine to the exposure stage and a cutting device for cutting the light-sensitive material into single sheets.
Such apparatus and methods are known from various patents and patent applications dealing with photographic printing devices.
The published German Patent Application No. DE-OS 197 47 122 describes a photographic printing apparatus with both an analog and a digital exposure unit that is used to expose photographic paper. This apparatus accommodates two paper magazines containing continuous rolls of printing paper. The printing paper is fed from the magazines, cut into single sheets and exposed in the exposure stage or, after removal from the magazine, is conveyed as a strip along a line exposure device, where it is exposed and then cut into individual sheets. The paper magazines are arranged on both sides of the exposure platform such that by choice paper can be taken from one magazine or paper can be taken from the other magazine. The magazines are designed such that paper with different widths or paper coated with different photographic emulsions can be used. This ensures that, with a continuously operating exposure device, two different types or two different widths of paper can be exposed.
However, since today it is common to make photographic prints in many different formats, providing two different paper widths is often not enough to create all desired printing formats in a continuously operating apparatus. To use paper with a third width, the above-noted apparatus must be stopped, the cassettes must be changed and the interrupted printing process must be restarted.
To avoid such an interruption of the printing process when exposing varying paper types or paper widths, the European Patent No. 0,570,651 A1 recommends equipping a photographic printing apparatus with a storage place for several paper cassettes containing rolled paper strip. The mouths of the cassettes are oriented next to one another, perpendicular to the transport direction of the material to be printed. A feeding device, with a carriage that can be moved perpendicular to the transport direction of the material to be printed, moves the material to be printed each time from one cassette mouth to the exposure device.
However, such a paper magazine arrangement consisting of several cassettes with different paper material strips is very large, and, together with the feeding mechanism, takes up a large volume of space in the printing apparatus. Moreover, the feeding device is a very sophisticated and expensive component in the printing apparatus. An additional disadvantage is the loss of time for transporting paper from a more distant cassette to the exposure stage.
It is, therefore, the principal objective of the present invention to develop an apparatus and method for exposing light-sensitive material, such as photographic paper, where the light-sensitive material can be continuously made available for exposure in a variety of different formats and types and within only a short amount of time.
This objective, as well as other objectives which will become apparent from the discussion that follows, are achieved, according to the invention, by a providing in the apparatus, in addition to the roll magazine, a cassette for storing light-sensitive material in the form of sheets. A transfer device transfers the sheet material from the cassette to the transport device or directly to the exposure stage.
The provision, in addition to the roll magazine, of a sheet cassette with light-sensitive material of a different format or a different surface, for exposure by the exposure device, makes possible the creation of an image on a material of different format or appearance, depending on the material loaded in the sheet cassette. Thus, a sheet cassette increases the possibility for variation with regard to the paper selection in the same way that an additional roll magazine does. However, the paper cassette requires less space and can, therefore, be positioned in close proximity to the exposure stage. Using a simple transfer device, the material from the cassette can be transferred directly to the exposure stage using a transport device, or can be transferred to the transport device that transports the light-sensitive material from the roll magazine to the exposure stage.
Although there is an increased demand for unusual formats, they are still rather rare in comparison to the typical formats provided by the roll magazine. It is, therefore, not necessary to provide an additional large roll of light-sensitive material to the exposure device for the exposure of these unusual formats. For the relatively low utilization of these unusual formats, it is sufficient to provide a stack of sheets of light-sensitive material in the exposure device, such that, on the one hand, the exposure of these formats is possible in the continuous operation of the photographic printing apparatus and, on the other hand, the functionality of the apparatus is not impaired by an over-dimensioned roll magazine. A sheet cassette with a transfer device can be easily accommodated in the apparatus and is significantly less complicated than a storage place with several cassette rolls that require a technically very sophisticated feeding device.
To become even more flexible in material selection, an additional cassette for light-sensitive sheet material can be provided in the exposure device. Depending upon the amount of space available in the apparatus, even three or more sheet cassettes with different materials can be accommodated in the apparatus. If more than one cassette is provided, it is prudent to design the transfer device in such a manner that it can be moved between the cassettes so that, with one movable transfer device, light-sensitive material can be taken from any desired cassette and transported to the exposure stage.
The transfer device described in the German Patent No. 36 10 660 for an X-ray film cassette loading apparatus can be used in the photographic printing apparatus according to the invention. In this X-ray apparatus, the X-ray film sheets are picked up using a suction device that can be moved between various X-ray film sheet cassettes. Of course, this design can be used for all other types of film sheets as well.
Such transfer devices with suction devices for transferring light-sensitive material from a sheet cassette to a conveyer device that transports the light-sensitive material to an image generation device are also suitable for isolating individual sheets when using only one sheet cassette in the exposure device. An example is provided in the German Patent No. 41 23 188.
The transfer device can also be equipped with rolls for removing the sheet material from the cassette. An example of this arrangement is described extensively in the European Patent No. 0,047,541.
If the sheets are removed with the use of rolls, a switching system that funnels the sheets taken from the various cassettes to a common transport path can be used instead of the robot-like moveable transfer device.
To simplify the removal of individual sheets from the cassette, a lifting arm that lifts the stack of sheet material in the cassette may be provided at the bottom of the sheet cassette, such that the top sheet is positioned at the removal slot where it can be easily grasped by the transfer device and removed from the cassette. An example of this device is provided in the German Patent No. 36 00 103.
A sheet cassette can be built into the apparatus and loaded from the outside with a light-tight stack of light-sensitive material. However, the cassette can also be inserted into the apparatus by means of an insertion opening such as an insertion slot. If the cassette is to be inserted into the apparatus by means of a slot, it must be possible to close the slot in a light-tight manner. It is advantageous if the slot is designed such that cassettes of varying sizes can be accommodated. In this case, it is possible to provide various formats and material surfaces for the exposure of images by simply changing handy sheet cassettes.
For example, three different widths of light-sensitive material can be provided for exposure in an exposure device by providing two roll magazines and one cassette. By cutting the roll material into pieces of different lengths, a considerable number of formats can already be realized.
Providing a stack of light-sensitive sheet material in addition to the material rolls is advantageous both for conventional exposure devices that illuminate a film negative and print it onto photographic paper via printing optics and for digital exposure devices that expose scanned image data or, other digital data onto light-sensitive material. With digital apparatus, laser devices, pixel-controlled light modulators that are illuminated by a light source, or light emitting pixel-controlled light sources such as LEDs, can be used as exposure units.
Depending on the exposure unit, either a flat exposure stage or a curved exposure roll can be used, and the transport device for the light-sensitive material must be adapted to it.
For a full understanding of the present invention, reference should now be made to the following detailed description of the preferred embodiments of the invention as illustrated in the accompanying drawings.